Solder feeding device



Feb. 17, 1953 J. E. COWLES 2,628,585

SOLDER FEEDING DEVICE Filed May 12. 1949 5 Sheets-Sheet l 5 vllmumll 14 /9 m ln/ i. MWXII'BIIW h I o I N VEN TOR.

Feb. 17, 1953 J. E. COWLES 2,628,585

SOLDER FEEDING DEVICE Filed May 12. 1949 5 Sheets-Sheet 2 I N VEN TOR.

Feb. 17, 1953 J. E. cowLEs SOLDER FEEDING DEVICE 5 Sheets-Sheet 3 Filed May 12. 1949 64 m0 ya J0 WW W W W 5 H W 4 m d m Feb. 17, 1953 .J. E. COWLES 2,623,585

SOLDER FEEDING DEVICE Filed May 12. 1949 5 Sheets-Sheet 4 IN VEN TOR,

4/0/72? .5. COW/F45 BY Patented F eb. 17, 1953 hil'i'ED STATES iih sihhl'l' OFFICE S-QLDER FEEDING DEVICE John E. Cowles, Philadelphia, Pa.

Application May 12, 1949, Serial No. 92,907

3 Claims. 1

My invention relates to automatic soldering machines, and relates particularly to a machine wherein the soldering heat is developed electrically.

It is an object of my invention to provide a semi-automatic machine for mass-producing any type of soldered connection for which the machine may be set up.

Another object of my invention is to provide a machine of the above description in which most of the various steps of the soldering operation are performed automatically, wi h automatic or manual control thereof.

Other objects of my invention are to provide an improved device of the character described, that is easily and economically produced, which is sturdy in construction, and which is highly efilcient in operation.

With the above and related objects in view, my invention consists in the details of construction and combination of parts, as will be more fully understood from the following description, when read in conjunction with the accompanying drawings in which:

Fig. l is a perspective view of the front of a cabinet embodying my invention.

Fig. 2 is a perspective view of the rear of my invention, the cabinet being opened to expose the power supply and controls thereof.

Fig. 3 is a top view of my solder advancing mechanism.

Fig. 4 is a side view of the solder advancing mechanism.

Fig. 5 is a schematic diagram of the pneumatic circuit used in my invention.

Figure 6 is a schematic diagram oi the electrical wiring of my invention.

Figure 7 shows a fixed electrode.

Briefly, my invention "functions by holding the work between a fixed, high-resistance carbon electrode which is shaped to receive the work a movable, low resistance clamping electrode, the latter being operated by compressed air. A stepdown transformer connected to the electrodes sends a heavy current of electricity through the electrodes and the work, and develops heat in the high resistance electrode, rincipally at the point of contact with the work. After the work has been brought to soldering heat, solder is applied and withdrawn and the transformer is then doenergized. The clamping electrode is then raised to allow the work to be changed. Electronic timing circuits control the sequence duration of the various steps described.

Referring now to the drawings, wherein similar reference characters designate similar parts, I show a soldering machine comprising a work bench position in the front designated generally as A, an upper cabinet B, and a lower cabinet C. The work bench A supports the work-receiving fixed electrode It the pneumatic cylinder, generally designated as D which actuates the movable electrode I 4 and the solder feed, generally designated as E. The upper cabinet B houses the heating current transformer l2, the adjustable controls for timing the various operations, the indicator lamps, the air pressure gauges, and the operating switches and relays. These are illustrated pictorially in Figs. 1 and 2.

A separate hinged chassis, designated generally as F, supports the electronic tubes and timing circuits.

The lower cabinet C houses the solenoid-operated air valves which actuate the pneumatic elec trode D, and if desired, may house an electric motor-driven air-compressor (not shown).

The solder feed E, shown in Figs. 3 and 4, is a solenoid-actuated unit for intermittently advanc ing a length of wire solder against the heated work. The unit consists of a base plate 50 carrying at one end a solenoid 52, through the bore of which passes an armature shaft 56.. The rear end of the armature shaft 54 terminates in a yoke 56. One side of the yoke carries a forwardlyextending jaw 53 pivoted upon a pin 69 which extends downwardly into a guide slot 82 in movable plate 84. Similarly, the other side of the yoke carries a jaw 66 which pivots upon a pin 558, the pin extending within a guide slot ill in plate 66. The jaws 58 and 56 are urged together by pressure springs l2 and M respectively which are attached to the yoke sides. An armature return spring 16 encircles the shaft 54, and a bridge is is attached to the top of the yoke.

The wire solder is supplied from a reel (not shown) and the free end passes through an aperture an in a post 32 at the rear end of the plate 64. The solder then passes between a pair of forwardly-extending spring-loaded jaws 84 and at, through an aperture 88 in the stop-screw post 99, through the yoke jaws E8 and 66, then through an axial passage 92 in the armature 54 and finally through an aperture 34 in a plate 96 attached to the forward end of the solenoid 52. The stop screw post 9% is mounted upon the slidable plate 64.

A. compression spring 58 extends between a lug lot! on the underside of plate 64 and the base post i t2, the latter carrying a thumbscrew its for adjusting the compression of the spring 98. A

thumbscrew I08 in post 82 serves as a back stop adjustment for the plate 64.

The feed unit functions as follows. At the proper point in the soldering cycle, the solenoid 52 is energized, drawing the armature 5 3 forward.

The yoke jaws 58 and 65 seize the solder and draw it forward compressing the armature spring 76. When the pins 68 and 68 strike the forward ends of their guide slots, the movable plate 65 is also moved forward, compressing spring 93. The rear jaws 8t and 85 permit the wire to move between them in a forward direction. Meantime the work has been placed upon the fixedcarbon block It by the operator, and the pneumatically operated movable electrode I4 descends, clamping the work against the carbon block It. The current transformer I2 is energized heating the work. At this time the solder is fed against the heated juncture. When the solenoid 52 is de-energized, the armature 54 and the movable plate 68 retract, withdrawing the solder from the work. The plate 65 is stopped first by the rear stop screw 588. As the yoke jaws continue to move back, they allow an additional length of solder to pass through, before the bridge I8 strikes the adjustment stop screw I08 in post 90. The solder feed thus automatically feeds a measured length of solder to the Work, and subsequently withdraws the solder slightly, to prevent an excess from being melted oil.

The pneumatic circuit shown in Fig. 5, consists of the following elements. Compressed air (which may be furnished by a small compressor not shown) passes through a filter 29 into a cross connection 22 at which point a gauge 25 shows the line pressure. The air then passes into an expansion valve 26 which reduces the pressure, as measured by gauge 28, to the necessary valve for operating the pneumatic cylinder D. The air then passes through a solenoid valve 38 which is opened at the proper time by the electronic heat ing timer described later, through the cylinder speed control 32 into the pneumatic cylinder D, forcing the upper electrode l4 into contact with the work for a pre-determined interval of time. The solenoid valve 38 then closes, shutting off the air supply from the expansion valve 26 and releasing through its exhaust port the air trapped in the cylinder D. An internal sprin 32 raises the electrode i l from the work. The cylinder speed control varies the time required for the electrode I d to operate and may be set by the operator of the machine.

Air is also used to cool the work after the electrode I4 is raised. This air is conducted from the cross fitting 22 to a second expansion valve 34, thence through a second solenoid valve 35 to a flexible Venturi tube 38 which is aimed at the soldered juncture in the work. The solenoid valves 35 and 28 operate alternately, so that the cooling air is blown upon the work as soon as the cylinder D releases it. In certain instances, this cooling air may also be used to blow the soldered work oif the carbon block Ill, into a receptacle for finished work, reducing the machine operators task to that of inserting the new work only.

The electrical controls now to be described have various functions, depending upon the mode in which the machine is to be used.

In the manual mode of operation, the len th of time of heating cylinder air pressure and solder feed are still determined automatically, but they are initiated by the operator, using the food pedal i=6. Manual operation is useful for small lots of No. 1 controls the heating timer tube Vi.

4 work and for familiarizing the operator with the machine.

In the automatic mode, the operator manually inserts the work upon the fixed electrode iii and then starts the machine the first time by pressing the foot pedal !6. The machine then automatically clamps the work, passes a heavy current of electricity to heat the point to be soldered, feeds a measured length of solder into this heated point, and then cools the work. The operator then continues to supply new work to the machine. One timer cyclically controls the heating time, the air cooling time and the pneumatic cylinder cperation. A second timer controls the solder feed operation, synchronizing it at the proper delay interval with the heating operation. The wiring diagram of the machine is shown in Fig. '6. Five multi-contact relays are used to connect the various circuits for either manual or automatic operation, as selected by DPDT switch I58. Relay Relay No. 2 is operated by VI and in turn alternately energizes the air cooling solenoid valve 36 and through relay N0. 5, the cylinder air valve solenoid 28 and the current transformer i2. Relay N0. 4; controls the solder feed timer tube V2, which energizes relay No. l. The latter relay energizes the solder feed solenoid 52. Each timer tube has its own rectifier tube, which supplies the plate. screen and grid biasing voltages required. Each timer tube has its control grid shunted by acapacitor which operates in combination with adjustable charging or discharging resistors to vary the grid bias over a pre-determined interval so as to render the tube more or less conductive for that interval. A. 0. power is supplied from the mains through the switch I 36 to the high side I22 and the low side l2. The electrodes I8 and M connect to the low voltage secondary winding of the current transformer I2. The primary winding of this transformer is bridged by a pilot lamp i253, and. has one side connected to the high side 522 of the line, and its other side connected to the low side I24- of the line through pole A of relay No. 5 and a manual switch I26. The cylinder air solenoid valve 28 is connected to the high side I22 of the A. C. line, and to the low side I26 of the A. C. line through pole B of relay No. 5.

The heaters of the heating timer pentode VI, its power supply rectifier V3, the solenoid feed timer pentode V2 and its power supply rectifier V4, are wired in series with a line voltage dropping resistor I32, and. Timer On-Oif switch I33. A pilot lamp I35 indicates that the timers are operating. Diode A of V3 supplies D. C. positive voltage for the plate and screen of VI, the latter being shunted by a filter capacitor I34. The heating timer V! is cathode biased by resistor I36, and its plate current energizes relay No. 2. Diode B furnishes a negative voltage to a potentiometer I 38 shunted by a filter capacitor I46, the output voltage being used to bias the grid of Vi to cut-off, through an adjustable high-resistance control I 52. This control I42 in combination with capacitor I44, determines the length of time that relay No. 2 is energized, and since relay No. 2 when energized operates relay No. 5 thru contacts 7-8, the time interval for clamping and heating the work is thereby determined for automatic operation. At the end of this time interval, the control grid of VI becomes sufficiently negative to cut off plate current, relay No. 2 deenergizes, and the grid bias is discharged through adjustable discharging resistor I46. Simultaneously, relay No, 5 is de-energized, cutting off the cylinderair pressure and the heating current and the cooling air valve solenoid 3B is energized instead. When the control grid bias has been sufliciently dissipated through resistor I46, VI again conducts, relay No. 2 again operates, and the clamping and heating portion of the cycle repeats. This alternate conduction and non-conduction of VI constitutes the method by which automatic timing is achieved, and a full description of automatic operation will now be given. V2, it should be noted, functions in exactly the same manner as VI, except that it is synchronized therewith and controls the solder feed solenoid 52. DPDT switch IE9 is thrown to automatic position and foot pedal switch I8 is operated. The field of relay No. l is thereby connected to line side I22 through switch I8, energizing the field. Contacts I and 2 of relay No. l, in series with contacts 4 and 5 of switch I50 now shunt switch I8, and keep the field energized even after switch I8 is released. The control grid of VI is now connected, through contacts I2 of switch I 50, and contacts 3 I- of relay No. 1, and contacts 5-45 of relay No. 2 to the discharging resistor I45. The grid having zero bias, VI conducts, and relay No. 2 becomes energized. Contacts 'I-8 of relay No. 2 complete the A. C. circuit to relay No. 5, which in turn completes the A. C. circuits of the heating transformer primary and the cylinder air valve solenoid 28. Contacts --I5 of relay No. 2 connect the control grid of VI to the bias charging resistor Hi2, whose value determines the length of time before VI again cuts oif. As contact 3 of relay No. 2 moves to the left, it touches contact I which is already touching contact 2. The high side of the line is thereby momentarily connected to the field coil of relay No. 4., through contacts 2-3 of relay No. 2, energizing relay No. l. As contact 3 of relay No. 2 continues to move left, it forces contact I away from contact 2, and holding current is supplied to relay No. 4 through contacts I3 of relay No. 2, contacts 5? of relay No. 3 (dc-energized) and contacts i-2 of relay No. 4 (energized). The solenoid feed timer tube V2 is cathode biased by resistor I52, and its plate current operates relay No. 3. Plate and screen voltage is furnished by diode A of rectifier tube V i, and is filtered by capacitor Diode B of V4 furnishes negative grid-bias voltage to a por tentiometer I56, which is filtered by capacitor I58. The control grid of V2 is shunted by capacitor I51! which is part of the timing network.

When relay 4 becomes energized, the control grid of V2 is connected to a grounded discharging resistor I62 through contacts 2--3 of relay No. 3 (dc-energized) and contacts l5 of relay No. a. As soon as the bias on the control grid of V2 has been dissipated through resistor I52, V2 conducts, and energizes relay No. 3.

Contacts 4 and 5 of relay No. 3 complete the A. C. circuit of the solder feed solenoid Contacts I and 2 of relay No. 3 co' ct the control grid of V2 to a source of cut-or bias through an adjustable charging resistor i 6. This resistor determines the length of time for which V 2 conducts plate current; and consequently, the time for which relay No. 3 remains energized. Con tacts 6'! of relay No. 3 open, deenergizing relay No. 5. As soon as the control grid of V2 becomes suniciently negative through resistor Ifi, V2 cuts oii' and relay No. 3 is de-energized. The solder-feed solenoid current is interrupted at contacts 3-4 of relay No. 3, and the control grid of V2 is connected to a source of cut-off bias through contacts 2-3 of relay No. 3, and contacts 5 6 of relay No. 4. Accordingly, V2 will not conduct again until relay No. 4 is energized by relay No. 2, as described previously. The function of the discharging resistor I62, acting in combination with grid capacitor ISO, is to delay the operation of the solder-feed solenoid until the work has become suiiiciently heated to melt the solder.

The entire cycle of automatic operation has now been described in detail. In summary, the cycle is initiated by momentarily closing foot pedal switch I8, which causes the heating timer to operate cyclically. The heating timer in turn operates the solder-feed timer, and a delay circuit in the solder-feed timer causes it to feed at the proper time in each cycle.

On manual operation, switch I59 is thrown to manual position (down). After the operator has positioned the work upon the fixed electrode Iii, he depresses the foot pedal switch I 8. This completes the A. C. circuit to the field of relay No. 1, which when energized closes the following circuits.

Contacts I--2 of relay No. l energize relay No. 4 through switch I8, contacts 56 of switch I59 and contacts I2 of relay No. 2 (dc-energized). Contacts 61 of relay No. 1 ground the grid of :tube VI through contacts 2-3 of switch I53, causing the tube VI to conduct, and thereby en ergizing relay No. 2. Thus, the cylinder air valve solenoid 2-8 and the heating transformer I2 are operative as long as the foot pedal is held down. Relay No. 4 operates in the manner described for automatic operation, causing the solder-feed timer tube V2 to operate and feed solder to the work. Since relay No. 4 is actuated thru relay No. 2, solder is fed to the work each time the foot pedal I5 is depressed, after the delay interval determined by the setting of resistor I52.

In order to properly heat the work, I make the lower, shaped electrode I0 preferably out of high-resistance carbon, to develop heat. The upper, movable electrode I4 is made of low-r sistance carbon. It is necessary to use carbon to prevent the work from sticking to the electrode. The flux used in the soldering operation may be incorporated in the solder itself. The movable electrode I 4 is connected to the current transformer by a 'pair of heavy flexible cables I!) made of stranded copper wire. It is possible to use this machine for light duty resistance welding although the carbon electrodes would then be replaced with copper electrodes.

Although my invention has been described in considerable detail, such description is intended as being illustrative rather than limiting since the invention may be variously embodied and the scope of the invention is to be determined as claimed.

I claim as my invention:

1. In an automatic soldering machine, a device for feeding the solder toward a workpiece comprising a base, a solenoid mounted at one end of said base, a hollow armature slidably positioned in said solenoid and having a portion thereof extending outwardly of said solenoid, a yoke mounted on that end of the armature which is located outwardly of said solenoid, a spring connected to said armature to bias it away from said solenoid, a plate slidably mounted on the end of said base which is opposite to said solenoid, said plate being spring-pressed away from said solenoid, said yoke being connected to said plate by a lost motion connection, and means on said yoke and on said plate to grip a length of solder which is adapted to "be threaded through said hollow armature and to extend toward a workpiece spaced from said feeding device, whereby said solder is moved toward said workpiece when said solenoid is actuated and moved away from said workpiece when said solenoid is de-energized.

2. The device of claim 1 wherein said gripping means comprise a pair of spring-pressed jaws on said yoke and a pair of spring-pressed jaws on said plate, said jaws on said plate being adapted to allow movement of said solder only in a direction toward said solenoid.

3. The device of claim 1 wherein an adjustable stop means is mounted on said base to limit movement of said plate away from ,said solenoid and wherein an adjustable stop means is provided on said plate to limit movement of said yoke away from said solenoid.

JOHN E. COWLES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

